Search

Heavy metal removal from wastewater has emerged as a major environmental concern on a global scale. The primary objective of this study was to determine how well lead (Pb) can be removed from wastewater by adsorptive processes using a chitosan-oligosaccharide-based hybrid (chitosan oligosaccharide (COS)/carboxymethyl starch binary blend material developed in the presence of glutaraldehyde (Glu). The amine and hydroxyl groups in the COS structure, the hydroxy and carboxy groups in the carboxymethyl starch, and the imine groups created when the amino group of COS reacts with the aldehydic group glutaraldehyde aid in the removal of Pb ions. FTIR, SEM, and X-ray diffraction were used to characterize the COS/CMC + Glu blend. Batch adsorption experiments, in which various factors including the impact of initial concentration, the dose of adsorbent, and the duration of contact, were used to analyze the removal of ions. The pH-dependent adsorption of Pb ions peaked at pH 5. The favorability of the reported experimental data was confirmed using various theoretical models, such as the Freundlich, the Langmuir isotherms, and pseudo-first- and pseudo-second-order kinetics. Adsorption was best fit by the pseudo-second-order and Langmuir isotherms. [ABSTRACT FROM AUTHOR]

In this study, magnetic material was synthesized using iron salts, then silicon-specific material was used to gain porosity, straight-chain polyacrylamide (PAM) was modified to give the surface functional properties, and the final product synthesized Fe3O4/SiO2/PAM nanocomposite material. Heavy metal (Pb and Cd) removal studies were carried out with the synthesized composite material, considering the central composite design and response surface methodology (CCD-RSM) optimization model. The effects of various parameters, for example, the initial concentration, pH, adsorbent dose, temperature and contact time, were investigated as a part of this study. To optimize these parameters, the CCD-RSM model was applied to design the experiments. Analysis of variance (ANOVA) was applied to evaluate statistical parameters and investigate interactions of variables. In the designed experimental set, the amount of adsorbent (30 mg), pH 7.0 value, temperature (40 °C), initial concentration of Pb (80 mg/L) and Cd (20 mg/L) and 90 min contact time were determined as the optimum conditions. The high coefficient of determination of both metals showed good agreement between experimental results and predicted values (R2 0.99; 0.95). TEM, SEM, XRD, FTIR, BET and Zeta potential analyses were performed to characterize the structure and morphology of the adsorbent. In Pb2+ and Cd2+ heavy metal removal studies, maximum adsorption capacities were determined as 66.54 and 13.22 mg/g, respectively. Additionally, adsorption isotherms, adsorption kinetics and thermodynamic modeling studies were conducted. Features such as large surface area and high adsorption capacity of the synthesized nanoparticles were observed. In this study, Fe3O4/SiO2/PAM demonstrated its potential as an effective adsorbent for the removal of heavy metal ions present in simulated wastewater samples. In particular, we can say that the material has a strong selectivity, as well as a high affinity for Pb(II) ions. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) have emerged as effective biotechnological solutions for wastewater treatment in recent decades. While plants are recognized components of these systems, their specific role in nutrient and heavy metal (HM) uptake warrants further investigation. This study assesses the efficacy of a vertical flow constructed wetland (VFCW) unit planted with Phragmites australis in treating HM-laden wastewater. Through standard methods, wastewater samples from inlet and outlet were analyzed for HMs (Cd, Zn, Pb, Cu), alongside plant and sediment samples. Planted CWs demonstrated remarkable removal efficiencies: 89.34% for Cd, 76.27% for Zn, 68.14% for Cu, and 66.42% for Pb, surpassing unplanted systems (18.27% to 33.16% removal). Notably, P. australis exhibited strategic pollutant absorption, with highest HM concentrations below-ground. Though above-ground HM accumulation was relatively minor, it exceeded soil concentrations. Analysis of accumulation factors confirmed roots and rhizomes as primary bio-accumulators, with transfer factor values (Cd > Pb > Zn > Cu) indicating efficient uptake. These findings underscore the pivotal role of P. australis in enhancing HM removal within VFCW systems, emphasizing the importance of plant-based strategies in HM remediation. Recommendations include further exploration of plant-assisted methods to optimize HM treatment in CWs. [ABSTRACT FROM AUTHOR]

Phase pure sodium trititanate (Na2Ti3O7) and hexatitanate (Na2Ti6O13) nanorods were controllably synthesized using sodium carbonate and titanic acid as sodium and titanium precursors by calcination at 850 °C for 12 h. The adsorption properties of trititanate and hexatitanate nanorods for the removal of heavy metal ions, Ni2+ and Pb2+ from simulated wastewaters at pH of 3‒7 and 20‒65 °C were investigated. The adsorption of Ni2+ and Pb2+ ions on sodium trititanate and hexatitanate nanorods are through ion exchange and electrostatic adsorption. The adsorption of Ni2+ and Pb2+ ions could be well fitted by the pseudo-second order adsorption kinetics and Langmuir adsorption isotherm. Based on the Langmuir adsorption isotherm, the adsorption capacities of naked sodium trititanate nanorods for Ni2+ and Pb2+ from simulated wastewaters at 20 °C and pH 7 are 104.17 and 89.85 mg∙g‒1 while the adsorption capacities of naked sodium hexatitanate nanorods are 95.69 and 76.69 mg∙g‒1, respectively. Sodium trititanate nanorods exhibit higher adsorption capacities for heavy metal ions from wastewaters than sodium hexatitanate nanorods because the former has richer Na+ ions for ion exchange with heavy metal ions than the latter. The adsorption processes of Ni2+ and Pb2+ on sodium trititanate and hexatitanate nanorods are spontaneous. The phase pure sodium titanate nanorods may have practical application for the removal and enrichment of metal ions from wastewaters. [ABSTRACT FROM AUTHOR]

Background: Chicken eggshells, a common poultry byproduct, are rich in calcium and provide a sustainable source for producing calcium oxide nanoparticles (CaO NPs). Their use in eco-friendly synthesis aligns with the growing emphasis on sustainable materials for environmental and biomedical applications. Objectives: This study develops an eco-friendly method for synthesizing CaO NPs from chicken eggshells, characterizes their physicochemical properties, and evaluates their antibacterial and antifungal activities. It also tests their effectiveness in removing heavy metal ions (Pb2+, Cr2+, Cd2+, and Hg2+) from aqueous solutions. Methods: CaO NPs were synthesized by calcining chicken eggshells at 700°C for 7 h. Comprehensive characterization included analysis of crystalline structure, morphology, optical properties, bandgap energy, chemical composition, and thermal stability. Antibacterial and antifungal activities were tested using the wellagar diffusion method. Batch adsorption experiments evaluated heavy metal ion removal under varying conditions of pH, temperature, stirring time, and adsorbent concentration Results: The synthesis produced spherical, single-crystal CaO NPs with diameters ranging from 5 to 30 nm and a crystalline size of approximately 20 nm. The nanoparticles had a bandgap energy of about 4.7 eV. Significant antibacterial activity was observed against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli, with increasing inhibition zones correlating with nanoparticle concentration. The CaO NPs also effectively inhibited Candida albicans. For efficient metal ion removal, the optimal conditions were found to be 30 min at pH 6 with 40 mg of CaO NPs at 25°C, achieving recovery rates of 98% for Pb2+, 97% for Cd2+, 97% for Cr2+, and 97% for Hg2+. For near-complete removal, extending the process to 70 min at pH 6 with 40 mg of CaO NPs at 45°C achieved the highest recovery rates: 99% for Pb2+, 98% for Cd2+, 99% for Cr2+, and 99% for Hg2+, though this approach involves higher energy and cost. Conclusion: CaO NPs derived from chicken eggshells are effective antibacterial agents and adsorbents for heavy metal removal. These findings highlight their potential for sustainable applications in environmental and biomedical fields. [ABSTRACT FROM AUTHOR]

Abstract\nNovelty statementCoal mine drainage (CMD) is an environmental threat due to its high volume, low pH, presence of toxic metals, and absence of biodegradable organics. The present study aims to treat CMD in a horizontal sub-surface flow constructed wetland (CW) using dairy wastewater as an organic source. CW was planted with Typha angustifolia. Characteristics of synthetic CMD were (except pH, all unit mg/L) pH 1.9; Fe: 100, SO42−: 1,000, Mn: 6, Zn: 5, Co: 1, Ni: 1, and Cr: 1. CMD was mixed with synthetic dairy wastewater (pH: 5.05, COD: 2,700 mg/L, BOD: 1,600 mg/L) in the ratio of 3:1. Alkalinity of 120–190 mg/L CaCO3 was generated and effluent pH improved from 2.2 to 6.6. Metals precipitated as metal sulfide or hydroxide. Sulfate removal was hindered due to the synergistic toxicity of several metals. Except for Mn, all other effluent parameters were within the discharge limit for disposal in inland surface water.There is limited information available on the advantages of using organic rich wastewater as a substrate for treatment of low carbon coal mine drainage (CMD). Coal mine drainage was mixed with dairy wastewater and treated in horizontal flow constructed wetland. Organic removal, metal removal, sulfate removal, and pH improvement of mixed wastewater are investigated in the present study. [ABSTRACT FROM AUTHOR]

ABSTRACT The removal of heavy metal ions from wastewater often necessitates the use of ion exchange resins. Current methods for assessing ion exchange efficiency are indirect and destructive. Some heavy metal ions, such as Cu2+ and Ni2+, are paramagnetic and influence the NMR relaxation times of water protons. NMR relaxometry can therefore be utilized to track the removal of these ions by ion exchange resins. In this study, we use relaxometry to monitor in situ the loading with Ni2+ and Cu2+ of Amberlite IR120 and Dowex Marathon MSC resins, with the resin column inserted into a low‐field NMR device. The multiexponential transverse relaxation curves were fitted using a biexponential model. Before and during the loading of the resin, the water with the slowest relaxation corresponds to treated water (free of Ni2+ or Cu2+) flowing between the resin beads. After saturation, the slowest fraction corresponds to the untreated solution (containing Ni2+ or Cu2+) flowing between the resin beads saturated with paramagnetic ions. The evolution with time of the transverse relaxation rate and the amplitude of the slowly relaxing water fraction shows a clear transition, occurring later at the bottom of the resin bed compared with the middle and top. This is interpreted as an indication of the saturation of the studied zone with paramagnetic ions, confirmed by the quantification of Ni2+ or Cu2+ in the effluent using AES spectroscopy. This proof‐of‐concept study demonstrates that NMR relaxometry can be used in situ to monitor the loading of a resin bed with paramagnetic ions. [ABSTRACT FROM AUTHOR]

AbstractA cellulose xanthate (CX) based polymer hydrogel has been synthesized using free radical graft polymerization technique. Two monomers Acrylic Acid (AA) and Acrylonitrile (AN) were reacted with cellulose xanthate to synthesize the desired hydrogel CX-g-poly(AA-co-AN). The synthesized hydrogel has been characterized by various techniques viz. Thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV), Field emission scanning electron microscope (FESEM) and Point zero charge (PZC). This hydrogel has been employed for the removal of toxic metal ions from wastewater. The maximum percentage removal has been found to be 97.5 (±4.87)% for Cu2+ ions and 96.1 (±4.80)% for Co2+ ions under optimum pH 6. The calculated adsorption capacities have been found to be 330.03 (±35.3) mg/g for Cu2+ ions and 325.73 (±22.4) mg/g for Co2+ ions using the Langmuir Adsorption isotherm model. The thermodynamic parameters depicted that the process was endothermic, and spontaneous. The adsorption kinetics data shows excellent fit with pseudo-second-order kinetic model. The synthesized hydrogel exhibits a high swelling ratio of 846.85 (±42.36) g/g and retention ratio of 50.12 (±2.50) % in distilled water. Also, the synthesized hydrogel showed good reusability, exhibiting percentage removal 83.2% for Cu2+ ions and 81.3% for Co2+ ions in the fifth cycle. [ABSTRACT FROM AUTHOR]

AbstractThe Guar Gum Xanthate based hydrogel GGmX-g-poly(AA-co-HEMA) has been successfully synthesized by using the graft copolymerization of two monomers, acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) hydrogel. The synthesis follows the free-radical graft polymerization method. UV-visible spectroscopy (UV), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Point zero charge (PZC), and field emission scanning electron microscopy (FESEM) were employed for the characterization of the synthesized hydrogel. This hydrogel has shown a high swelling ratio of 430.2 g/g and retention of 75.82% in distilled water which is a notable result. By using GGmX-g-poly(AA-co-HEMA) hydrogel, the maximum percentage of heavy metal ions removal from wastewater was found to be 98.5(±1.5)% and 97.1(±1.5) at optimum pH 6 and 6.5 for Cu2+ and Ni2+ solutions respectively. The Langmuir adsorption isotherm fits best for the adsorption data indicating a monolayer adsorption with maximum adsorption capacity of 423.72 (±26.1) mg/g and 404.85 (±31.4) mg/g for Cu2+ and Ni2+ ions respectively. The pseudo-second-order kinetic model provides the most accurate depiction of adsorption kinetics with rate constant 9.1 × 10−4 (±1.37×10−4)g/(mg.min) for Cu2+ and 8.3 × 10−4 (±1.24×10−4)g/(mg.min) for Ni2+ ions, respectively. The negative ΔG value (-4.75 kJ/mol for Cu2+ and −3.26 kJ/mol for Ni2+ ions) and positive value of ΔH (57.55 (±5.41) kJ/mol for Cu2+ and 40.60(±5.37) kJ/mol for Ni2+ ions) suggested the process to be spontaneous, endothermic, and feasible. It has been found that the hydrogel has excellent regenerative capacity with the % adsorption has been found to be 84.8% for Cu2+ and 82.4% for Ni2+ ions for the fifth cycle. [ABSTRACT FROM AUTHOR]

Fungal biomass is as a cost-effective and sustainable biosorbent utilized in both active and inactive forms. This study investigated the efficacy of inactivated and dried biomass of Fusarium sp. in adsorbing Ni2+ and Pb2+ from aqueous solutions. The strain underwent sequential cultivation and was recovered by filtration. Then, the biomass was dried in an oven at 80 ± 2 °C and sieved using a 0.1-cm mesh. The biosorbent was thoroughly characterized, including BET surface area analysis, morphology examination (SEM), chemical composition (XRF and FT-IR), thermal behavior (TGA), and surface charge determination (pH-PZC and zeta potential). The biosorption mechanism was elucidated by fitting equilibrium models of kinetics, isotherm, and thermodynamic to the data. The biosorbent exhibited a neutral charge, a rough surface, a relatively modest surface area, appropriate functional groups for adsorption, and thermal stability above 200 °C. Optimal biosorption was achieved at 25 ± 2 °C, using 0.05 g of adsorbent per 50 mL of metallic ion solution at initial concentrations ranging from 0.5 to 2.0 mg L−1 and at pH 4.5 for Pb2+ and Ni2+. Biosorption equilibrium was achieved after 240 min for Ni2+ and 1440 min for Pb2+. The process was spontaneous, mainly through chemisorption, in monolayer for Ni2+ and multilayer for Pb2+, with efficiencies of over 85% for both metallic ion removal. These findings underscore the potential of inactive and dry Fusarium sp. biomass (IDFB) as a promising material for the biosorption of Ni2+ and Pb2+. [ABSTRACT FROM AUTHOR]

In this work, biochars were used as adsorbents to remove Cu, Cd, and Zn ions in a real stabilized leachate from a controlled landfill. Oak fruit shells biochar (OFSBC) and date palm fibers biochar (DPFBC) were obtained by pyrolysis of oak fruit shells and date palm fibers at 700 °C and 400 °C, respectively. OFSBC and DPFBC showed well-developed structures and high specific surface areas (520.16 m2/g and 470.46 m2/g, respectively). Equilibrium adsorption of heavy metal ions on DPFBC and OFSBC occurred after 4 h and 2 h of stirring. The removal efficiencies of Cu, Cd, and Zn ions were 97.01%, 94.40%, and 80.59% with DPFBC and 90.10%, 88.33%, and 76.16% using OFSBC, respectively. The Avrami fractional order model was appropriate for describing kinetic adsorption. Increasing the dose of adsorbent improves heavy metal ion retention. Thermodynamic tests have proven the spontaneous and endothermic adsorption of these heavy metals. The electrostatic attraction, ion exchange, complexation, metal-π bending, and surface precipitation and pore filling were regarded as the most predominant heavy metal retention mechanisms from the landfill leachate onto the biochar surface. Separately, the DPFBC showed the best performance than OFSBC regarding the improvement of leachate quality. Chemical oxygen demand (COD), biological oxygen demand (BOD5), ammoniacal nitrogen (NH3-N), and phosphorus (P) were respectively removed at an efficiency of 53.57%, 29.17%, 36.07%, and 37.5%, respectively. Thus, the results allow highlighting that the adsorption on DPFBC and OFSBC can be an effective alternative in the practice of landfill leachate treatment. [ABSTRACT FROM AUTHOR]

Different composition of mixed matrix membranes comprising Polyvinylidene fluoride (PVDF) as base polymer, Polyvinylpyrrolidone and Montmorillonite clay as additive was fabricated by phase inversion technique using N, N-Dimethylacetamide as a solvent. Furnished membrane samples were characterized by X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) for phase identification, functional group analysis, thermal stability, determination of surface morphology and textural features which show that PVP and MMT successfully modified PVDF membrane and resulted in PVDF/PVP/MMT mixed matrix membrane. Different membrane characteristics such as pure water flux, water content, porosity, shrinkage ratio, fouling recovery ratio and solute rejection were studied and calculated. The contemporary membrane (PPM5) having 5 wt. % of MMT represented the increase in pure water flux, porosity, and fouling recovery ratio from 13.8 Lm−2h−1, 33% and 52% to 19.8 Lm−2h−1, 85%, and 87%, respectively. The PPM5 also shows a reduction in shrinkage ratio from 19% to 7% and improved hydrophilicity which results in a solute rejection factor of 83% and 87% for Pb(II) and Cd(II), respectively, in comparison to other fabricated membranes. These membranes provide an economical and effective solution for wastewater treatment. [ABSTRACT FROM AUTHOR]

This study investigates the efficiency of a hybrid coagulation–flocculation process for the treatment of industrial wastewater from the steel industry. The novel method combines a natural coagulant, processed Rosehip Seed Powder (RSP), with a chemical coagulant, aluminum chloride (AlCl3), across varying concentrations and pH levels. The study simulated the pH 8 conditions of iron and steel industrial wastewater and examined the removal of heavy metals, total suspended solids (TSS), chemical oxygen demand (COD), and ammonia–nitrogen (NH3-N). At pH 8, the optimal coagulant dosage was determined to be 0.75:0.75 (g/g) of RSP/AlCl3 powder, resulting in high removal efficiencies across several parameters: 88.29% for COD, 91.85% for color, 99% for TSS, 93.11% for NH3-N, 94.3% for Mn, 98.5% for Fe, 96.7% for Zn, and 99.3% for Ni. The pH optimization demonstrated high removal efficiencies without pH adjudication. The removal of heavy metals at pH 8 demonstrated high efficiencies, with Mn, Fe, Zn, and Al achieving 99.00%, 90.6%, 95.73%, and 92.3%, respectively. These results suggest that no pH adjustment is required when using RSP/AlCl3 for the treatment of iron and steel industry wastewater through the coagulation method. [ABSTRACT FROM AUTHOR]

The present study emphasizes the utilization ability of less expensive industrial waste adsorbents such as fly ash (FA) to adsorb heavy metals from wastewater r to remove its constituent pollutants, amazing eco-friendly technology guarantees benefits with the decrease in the formation of dangerous solid sludge. In the extended experimental work program: parameters such as pH, contact time, and adsorbent dosages were conducted. The results showed a remarkable treatment equilibrium time after two hours. From all the factors, the pH ranges from 5 to 8 significantly influenced the elimination of heavy metals removal efficiencies, and the highest achieved uptake efficiency during the whole three hours of the experiment period was found to be 93%, 90%, 85%, 79 %, 75 % and 70% for Cu, Fe, Ni, Zn, Pb, and Cd respectively with an optimum fly ash treatment dose of 15 g/L. Based on several performance metrics and visual indicators, different predictive regression-based models for wastewater heavy metals removal efficiencies were developed and compared to the experimental data. The statistical validation indicators revealed that a high correlation was obtained. In addition, the experiment's data were utilized using the Langmuir isotherm model. The results of adsorption data were highly satisfactory statistically match providence to Langmuir heavy metals kinetics removal with mean values of 8%, 11%, and 93% for relative mean absolute error (MAE)rel, percent bias (PBIAS), and Nash-Sutcliffe efficiency (NSE) respectively. [ABSTRACT FROM AUTHOR]

Algae have emerged as a promising approach for the removal of heavy metals from wastewater due to their low-cost, efficient, and eco-friendly characteristics. The unique structural and biochemical properties of algae enable them to remove heavy metals from wastewater using various mechanisms, including physical adsorption, ion exchange, complexation, precipitation, phycoremediation, and bioaccumulation. Algal modification techniques such as pre-treatment, immobilization, and genetic modification are also discussed as means of enhancing the efficiency and specificity of heavy metal removal. Additionally, the regeneration of algal biomass is presented as a sustainable solution to the issue of algal disposal. [ABSTRACT FROM AUTHOR]

Featured Application: Chlorococcum dorsiventrale for effective heavy metal removal in wastewater treatment and environmental cleanup: bioremoval of cadmium, chromium, and lead. Heavy metals are one of the main threats to marine life and ecosystems and any remedial action in that regard is urgently required. The aim of this work is to study the bioremoval of cadmium, chromium and lead in a microalgae strain Chlorococcum dorsiventrale isolated from Tunisian coastal waters along with assessing its enzymatic and molecular responses. The microalgae were tested in artificial seawater to evaluate their capacity for phycoremediation in an aquatic environment. This strain tolerated exposure to Cd (II), Cr (VI), and Pb (II) and was able to grow for 14 days. Cd and Cr exposures elicited a decrease in chlorophyll, lipid and polysaccharide contents, whereas no damages were detected following Pb treatment. For protein content, no significant changes were seen except after Pb exposure which induced a slight increase after treatment with 5 mg/L. The assessment of stress defense-related gene expression using qRT-PCR revealed that exposure to Pb and Cr induced an up-regulation of catalase, superoxide dismutase and photosystem II protein D1 encoding genes. Moreover, heat shock protein 70 was slightly overexpressed. Removal efficiencies for Cr and Pb attained 89% and 95%, respectively. The mechanisms by which C. dorsiventrale removed Cr involved both intracellular and extracellular biosorption, while Pb was predominantly removed through membrane adsorption. This study highlights the potential of C. dorsiventrale as an efficient agent for the bioremediation of heavy metal-contaminated water, including industrial wastewater, thus paving the way for practical and environmental applications in pollution control. [ABSTRACT FROM AUTHOR]

Thallium, a highly toxic pollutant, shows greater toxicity to human than other common heavy metals such as mercury, lead, cadmium and its effective removal from wastewater gains great attention. The main restriction for the Tl+ removal is the interference of a high concentration of co-existing ions in wastewater. Therefore, the goal of the current work was to synthesis adsorbent with high selectivity for the Tl+ removal. Herein, the pore size sieving strategy was proposed and Prussian blue-impregnated biochar (BC@PB) particles was synthesized. More than 95% Tl+ can be removed even the concentrations of the coexistence ions (Na+, Cd2+, and Zn2+) 1,000 higher than the initial concentration of Tl+ (500 μg/L). BC@PB also showed large adsorption capacity (9365 μg/g) and more than 99% Tl+ (initial concentration, 500 μg/L) were removed in just 1 min. The BC@PB had excellent and stable Tl+ removal ability (> 99%) over a range of pH from 3 to 9, which covered the pH range of common thallium-containing wastewater. The density functional theory (DFT) calculation confirmed that not only hydrated volume but also the hydration free energy of ions, which governed the energy barrier for ions entering into narrow channels of BC@PB, played essential roles on the selectivity removal of Tl+. Overall, due to its high selectivity, high adsorption capacity and easy preparation process, the synthesized BC@PB particles based on the pore sizing sieving strategy, can be a promising candidate for the removal of thallium from wastewater. [ABSTRACT FROM AUTHOR]

Phosphorus-modified biochar has been proven to enhance the precipitation and complexation of heavy metal ions from wastewater. However, the current modification methods require large amounts of exogenous P and have high energy consumption. Hence, this study proposes and analyzes a strategy integrating biochar production, phosphorus wastewater treatment, dephosphorization waste recovery, and heavy metal removal. "BC-Ca-P" was derived from Ca-modified biochar after phosphorus wastewater treatment. The adsorption of Pb(II) by BC-Ca-P followed the Langmuir isotherm and pseudo–second–order kinetic models. The maximum adsorption capability of 361.20 mg·g−1 at pH 5.0 for 2 h was markedly greater than that of external phosphorous-modified biochar. The adsorption mechanisms were dominated by chemical precipitation and complexation. Furthermore, density functional theory calculations indicated that oxygen-containing functional groups (P-O and C-O) contributed the most to the efficient adsorption of Pb(II) onto BC-Ca-P. To explore its practical feasibility, the adsorption performance of BC-Ca-P recovered from an actual environment was evaluated. The continuous-flow adsorption behavior was investigated and well-fitted utilizing the Thomas and Yoon–Nelson models. There was a negligible P leakage risk of BC-Ca-P during heavy metal treatment. This study describes a novel and sustainable method to utilize dephosphorization waste for heavy metal removal. Article Highlights: Dephosphorization biochar waste was used to sustainably remove heavy metals from wastewater. Field-recovered dephosphorization biochar waste displayed high Pb adsorption capacity. Dephosphorization biochar for heavy metal removal is an eco–friendly waste–reduction and resource–utilization method. [ABSTRACT FROM AUTHOR]

Water pollution involves the coexistence of microplastics (MPs) and traditional pollutants, and how can MPs influence the adsorption of other pollutants by biochar during the treatment process remains unclear. This study aimed to investigate the influence of polystyrene microplastics (PS MPs) on the adsorption of cadmium (Cd) and ciprofloxacin (CIP) by magnetic biochar (MTBC) in the single and binary systems. MTBC was prepared using tea leaf litter; the effects of time, pH, and salt ions on the adsorption behaviors were investigated; and X‐ray photoelectronic spectroscopy (XPS) and density flooding theory analysis were conducted to elucidate the influence mechanisms. Results indicated that PS MPs reduced the pollutants adsorption by MTBC due to the heterogeneous aggregation between PS MPs and MTBC and the surface charge change of MTBC induced by PS MPs. The effects of PS MPs on heavy metals and antibiotics adsorption were distinctly different. PS MPs reduced Cd adsorption on MTBC, which were significantly influenced by the solution pH and salt ions contents, suggesting the participation of electrostatic interaction and ion exchange in the adsorption, whereas the effects of PS MPs on CIP adsorption were inconspicuous. In the hybrid system, PS MPs reduced pollutants adsorption by MTBC with 66.3% decrease for Cd and 12.8% decrease for CIP, and the more remarkable reduction for Cd was due to the predominated physical adsorption, and CIP adsorption was mainly a stable chemisorption. The influence of PS MPs could be resulted from the interaction between PS MPs and MTBC with changing the functional groups and electrostatic potential of MTBC. This study demonstrated that when using biochar to decontaminate wastewater, it is imperative to consider the antagonistic action of MPs, especially for heavy metal removal. Practitioner Points: Magnetic biochar (MTBC) was prepared successfully using tea leaf litter.MTBC could be used for cadmium (Cd) and ciprofloxacin (CIP) removal.Polystyrene microplastics (Ps MPs) reduced Cd/CIP adsorption by MTBC.Ps MPs effects on Cd adsorption were more obvious than that of CIP.Ps MPs changed the functional groups and electrostatic potential of MTBC, thus influencing MTBC adsorption. [ABSTRACT FROM AUTHOR]

Herein, we successfully modified wood sponge (WS) with Fe3O4 (MWS) to enhance its ability to adsorb five different oils, eight organic solvents, metal ions, and degrade methylene blue (MB) from wastewater. MWS, possessing over 96% porosity, exhibited remarkable sorption capacities of 26.79 g g− 1 for CCl4 and 21.00 g g− 1 for pump oil. Notably, MWS maintained high sorption capacity even after repeated use. Furthermore, MWS effectively removed toxic metal ions including As3+, Cr6+, and Pb2+ from real industrial wastewater, at pH 4 and 50 °C to levels suitable for drinking water. Also, MWS demonstrated excellent photocatalytic properties for degrading methylene blue dye. The photodegradation process involved the generation of superoxide anion radicals and the participation of hydroxyl radicals. The magnetic properties of MWS allow for easy remote retrieval using a magnet, making it a cost-effective and reusable solution for environmental remediation. [ABSTRACT FROM AUTHOR]

The removal of metal in the form of sludge can be termed an ECM process, having primary salient features consisting of the tool, workpiece, power supply and electrolyte solution. ECM is a potential nontraditional machining process that includes too many factors contributing to process performance. Therefore, obtaining optimal factor combinations for higher efficiency is complex. In this research work, machining parameters are voltage, powder concentration and electrolyte concentration, based on which material removal rate (MRR) and surface roughness (SR) are derived. Regression analysis, signal-to-noise ratios and analysis of variance (ANOVA) are performed to determine the optimal levels and to examine the effects of machining parameters on MRR and SR. The results derived from the experiments noticed that the MRR decreases when the voltage level is increased and surface roughness decreases for the applied voltage. In case of an increase in powder concentration, MRR decreases from range 4 to 6 and further reduces to 6–8. In case of SR, it additionally decreases on the maximum level of powder concentration. In electrolyte concentration, the MRR decreases on the increment of electrolyte and increases after a short period of time; simultaneously SR is increased from range value 10–20 and decreased with a maximum level 20–30 of NaCl solution. A comparison of MOORA-PCA and TOPSIS-PCA demonstrates the superiority of TOPSIS over MOORA technique. Statistical results (95% confidence level) indicate that the voltage, powder concentration, and electrolyte concentration affect the surface roughness by 69.50%, 8.67% and 14.59% in the electrochemical machining of d3 die steel. Therefore, the optimum combination of process parameters corresponding to voltage: 45 V, powder concentration: 4 g/L, and electrolyte concentration: 10 NaCl/L, respectively, were found to yield the desired result. The prediction accuracy of the TOPSIS-PCA hybrid approach model is found better than MOORA-PCA technique. [ABSTRACT FROM AUTHOR]

Most undeveloped and developing countries have adopted landfill as the ultimate disposal method for their Municipal Solid Waste (MSW). Leachate produced by a landfill site is highly dangerous, with high concentrations of organic and inorganic pollutants, ammonia and toxic heavy metals. Heavy metals commonly found in landfill leachate are copper, lead, mercury, cadmium, arsenic etc., The main objective of this research is to study the removal of heavy metals copper and lead, from synthetic leachate using TiO2 and Ag-doped TiO2 nanomaterials by a heterogeneous photocatalytic process. The photocatalytic experiments were conducted using a compound parabolic collector in sunlight. The design of experiment is used to obtain the minimum number of experiments for the study, to analyze the data and to understand the interaction between the process variables and their responses. Photocatalytic behavior of copper and lead removal has been demonstrated using an Artificial Neural Network (ANN) model. Characterization studies are conducted on TiO2 and Ag-doped TiO2 nanomaterials by XRD, SEM and EDX. At optimum parameters of the dosage 0.75 g/L, pH 5 and irradiation time of 100 min, copper removal from synthetic leachate was found to be 80.38% and 80.12%, lead removal efficiency was 97.2% and 96.34% for TiO2 and Ag-doped TiO2, respectively. The determination coefficient value obtained by RSM and ANN ensures that the developed model of copper and lead removal gives an accurate prediction. The kinetic study shows that, copper and lead removal by photocatalytic process are described well by a Langmuir–Hinshelwood kinetic model. [ABSTRACT FROM AUTHOR]

A novel class of hydrogels, rich in a variety of functional groups capable of interacting/complexing with metal ions was successfully synthesized. This was achieved by using acryloyl derivatives of natural α-amino acids, specifically ornithine and cystine. The δ-amino group of ornithine was modified with an acryloyl group to facilitate its attachment to the polymer chain. Additionally, N,N'-bisacryloylcystine, derived from cystine, was employed as the cross-linker. The hydrogel was obtained through a process of free radical polymerization. This hydrogel, composed only from derivatives of natural amino acids, has proven to be a competitive sorbent and has been effectively used to remove heavy metal pollutants, mainly lead, copper, and silver ions, from aqueous media. The maximum sorption capacities were ca. 155 mg·g−1, 90 mg·g−1, and 215 mg·g−1, respectively for Pb(II), Cu(II), and Ag(I). The material was characterized by effective regeneration, maintaining the sorption capacity at around 80%, 85%, and 90% for Cu(II), Ag(I), and Pb(II), respectively, even after five cycles. The properties of sorption materials, such as sorption kinetics and the effect of pH on sorption, as well as the influence of the concentration of the examined metal ions on the swelling ratio and morphology of the gel, were investigated. The EDS technique was employed to investigate the composition and element distribution in the dry gel samples. Additionally, IR spectroscopy was used to identify the functional groups responsible for binding the studied metal ions, providing insights into their specific interactions with the hydrogel. [ABSTRACT FROM AUTHOR]

The accumulation of organic dyes and heavy metals (HMs) in sewage sludge (SS) after wastewater treatment is a significant problem due to the non-degradable nature of these pollutants. Moreover, the simultaneous removal of HMs and dyes in the complex process of SS treatment, such as anaerobic digestion (AD), has become attractive. HMs and dyes present in SS can have a detrimental effect on anaerobic digesters. These pollutants not only inhibit the production of methane, which is crucial for biogas generation, but also affect the stability of AD treatment, which can result in failure or inadequate performance of the AD process. This review highlights a novel method of removing HMs and dyes from the AD process of SS through the use of biochar modified with polyvinyl alcohol (PVA) and chitosan (CTS). The applications of conventional biochar have been limited due to poor adsorption capacity. However, modification using PVA/CTS composites enhances properties such as surface functional groups, adsorption capacity, porosity, surface area selectivity, and stability. Furthermore, this modified version can function as an additive in AD of SS treatment to boost biogas production, which is a viable source for heat generation or electricity supply. In addition, the digestates can be further processed through plasma pyrolysis for the removal of HMs and dyes bound to the modified biochar. Plasma pyrolysis generates two major products: syngas and slag. The syngas produced can then be used as a source of hydrogen, heat, and electricity, while the slag can potentially be reused as an AD additive or as a biofertilizer in the agricultural sector. Additionally, this study addresses the challenges associated with this integration and biochar modifications, and offers an outlook on understanding the interactions between the modified biochar properties, microbial dynamics, and the presence of micropollutants to ensure the economic viability and scalability of this technology. This comprehensive review provides insights into the potential of PVA/CTS-modified biochar as an effective additive in AD systems, offering a sustainable approach to SS treatment and valuable resource recovery. [ABSTRACT FROM AUTHOR]

The present study aimed to use geopolymer materials synthesized from different fly ashes, which are promising for the adsorption of copper ions from aqueous solutions. The characterization of fly ashes and prepared adsorbents was performed by energy-dispersive X-ray spectroscopy (EDS) analysis, Brunauer–Emmett–Teller (BET) surface area analysis, and Scanning Electron Microscopy (SEM). Taguchi and ANOVA methods were used to predict the effect of different working parameters on copper ion removal by prepared geopolymers. Based on data obtained by the Taguchi method, it was found that the factor most influencing the adsorption process is the type of adsorbent used, followed by the solution pH, the reaction time, the adsorbent dose, and the initial copper ion concentration. The ANOVA results agree with the Taguchi method. The optimal conditions of the adsorption process were: fly ash C modified by direct activation with 2 M NaOH, at 70 °C for 4 h, solution pH of 5, initial pollutant concentration of 300 mg/L, 40 g/L adsorbent dose, and 120 min of reaction time. Copper ion removal efficiency was determined experimentally under optimal conditions, achieving a value of 99.71%. [ABSTRACT FROM AUTHOR]

The distribution and removal pathways of heavy metals within different sludge treatment wetlands (STWs) during different running periods in Northeast China have not been well studied. In this study, we examined three STWs, i.e. an STW with aeration tubes only (unit 1; U1), an STW with reeds and aeration tubes (unit 2; U2), and an STW with reeds only (unit 3; U3). The results showed that the levels of Cu as well as Zn accumulated faster within STW residual sludge, whereas the levels of Cd, Cr, Ni, and Pb accumulated more slowly and decreased slightly over time. The removal rates of heavy metals from the influent sludge by STWs ranged from 64.5% (Cr) to 92.2% (Zn). Reeds removed heavy metals from the STWs by direct absorption, and Zn was highly enriched in the reeds. The presence of reeds also promoted the spreading of heavy metals to the substrate layer and improved the removal of heavy metals in STWs. The mass of each heavy metal accumulated within the residual sludge of U2 and U3 was lower than that of U1, indicating that reeds could facilitate the removal of heavy metals. The STWs removed heavy metal mainly by substrate adsorption, and the mass percentage of heavy metals accumulated in the substrate ranged from 35.8 to 63.6%. [ABSTRACT FROM AUTHOR]

Improper disposal of municipal solid waste led to the release of heavy metals into the environment through leachate accumulation, causing a range of health and environmental problems. Phycoremediation, using microalgae to remove heavy metals from contaminated water, was investigated as a promising alternative to traditional remediation methods. This study explored the potential of Scenedesmus sp. as a phycoremediation agent for heavy metal removal from landfill leachate. The study was conducted in batch, continuous, and membrane bioreactor (MBR). In the batch system, Scenedesmus sp. was added to the leachate and incubated for 15 days before the biomass was separated from the suspension. In the continuous system, Scenedesmus sp. was cultured in a flow-through system, and the leachate was continuously fed into the system with flow rates measured at 120, 150, and 180 mL/h for 27 days. The MBR system was similar to the continuous system, but it incorporated a membrane filtration step to remove suspended solids from the treated water. The peristaltic pump was calibrated to operate at five different flow rates: 0.24 L/h, 0.30 L/h, 0.36 L/h, 0.42 L/h, and 0.48 L/h for the MBR system and ran for 24 h. The results showed that Scenedesmus sp. was effective in removing heavy metals such as lead (Pb), cobalt (Co), chromium (Cr), nickel (Ni), and zinc (Zn) from landfill leachate in all three systems. The highest removal efficiency was observed for Ni, with a removal of 0.083 mg/L in the MBR and 0.068 mg/L in batch mode. The lowest removal efficiency was observed for Zn, with a removal of 0.032 mg/L in the MBR, 0.027 mg/L in continuous mode, and 0.022 mg/L in batch mode. The findings depicted that the adsorption capacity varied among the studied metal ions, with the highest capacity observed for Ni (II) and the lowest for Zn (II), reflecting differences in metal speciation, surface charge interactions, and affinity for the adsorbent material. These factors influenced the adsorption process and resulted in varying adsorption capacities for different metal ions. The study also evaluated the biomass growth of Scenedesmus sp. and found that it was significantly influenced by the initial metal concentration in the leachate. The results of this study suggest that Scenedesmus sp. can be used as an effective phycoremediation agent for removing heavy metals from landfill leachate. [ABSTRACT FROM AUTHOR]

The column performance of silica‐coated, amino‐functionalized, superparamagnetic nanoparticles co‐integrated with Cynodon dactylon and Murraya koenigii plant extracts for the removal of CuII ions was evaluated. The co‐integrated nanoparticles were used as sorbent materials in fixed‐bed column studies, and the effects of inlet concentration, adsorbent bed depth, and flow rate were analyzed. Breakthrough time was calculated for various CuII inlet concentrations, depths of the adsorbent bed, and volumetric flow rates. Models such as Thomas, Yoon‐Nelson, and the bed depth model were evaluated to determine the experimental fit. The maximum breakthrough time for CuII ions of 1200 min was attained for a CuII inlet concentration of 100 mg L–1, sorbent bed depth of 3 cm, and volumetric flow rate of 1 mL min–1. [ABSTRACT FROM AUTHOR]

Industrial effluents pose a serious environmental problem, because they contain toxic contaminants mainly heavy metals that are the most dangerous to humans, animals, plants, and the environment in general. Phytoremediation using macrophytes is an adopted technique for the environment decontamination due to its efficiency and cost-effectiveness. The present study aims to highlight the capabilities of macrophytes to remove heavy metals from wastewater of Biskra region (Algeria). The methodology consists of filling out the filters planted with Arundo donax and Phragmites australis with raw industrial wastewater, then recovering decontaminated water after 15 days to assess removal of lead, copper, zinc, and iron. Both plants had shown a good efficiency for the removal of metals loaded in wastewater eliminating about 94 to 98% of initial concentration. In addition, calculated bioaccumulation factor (BAF) had confirmed the accumulation of heavy metals in different parts of experimental plants; recorded values of BAF > 1 allowed the consideration of Arundo donax and Phragmites australis as good hyper-accumulator plants. Obtained results confirm the efficiency of phytoremediation technology using macrophytes for the wastewater treatment in particular and the environment decontamination in general. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and application of MgO@SnO2 nanocomposite (NC), surface-modified with polyvinylpyrrolidone (PVP), to address heavy metal removal and hydrocarbon degradation in petroleum wastewater. The nanocomposites were eco-friendly produced using Pistacia lentiscus leaf extract and underwent thorough characterization through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy, and scanning electron microscopy (SEM) analyses, confirming their successful synthesis and modification. Adsorption studies evaluated the nanocomposites' efficiency in eliminating 11 heavy metals from petroleum wastewater. Results revealed impressive adsorption capacities, achieving complete Cr, Mo, and Sb removal within 20 min and nearly 99% removal of all tested metals within 30 min. Additionally, MgO@SnO2@PVP NC exhibited exceptional photocatalytic activity under sunlight irradiation, leading to an 88% hydrocarbon degradation and an 85% reduction in total suspended solids (TSS) in oily industrial water (OIW) after 30 min, outperforming MgO@SnO2 NC. The reaction kinetics followed a pseudo-first-order model, with rate constant (k) values of 0.041 and 0.090 min−1 for OIW and TSS, respectively. Furthermore, the nanocomposites showed excellent recyclability over five cycles. First-principles calculations confirmed robust adsorption between the nanocomposites and heavy metal ions, validating their binding efficacy. Biosynthesized MgO@SnO2@PVP NC proves effective and recyclable for removing heavy metals and degrading hydrocarbons in petroleum wastewater, presenting promising environmental remediation solutions. [ABSTRACT FROM AUTHOR]

This study addresses the critical issue of copper removal from wastewater due to environmental and health concerns. Choosing pandan leaves as a source of cellulose was a deliberate decision due to their abundant availability in nature and minimal ecological footprint. Through the utilization of these properties, this study synthesized nanocellulose with enhanced adsorption capabilities by employing chemical pretreatments, sulfuric acid hydrolysis, and acrylamide grafting with the aid of ceric ammonium nitrate (CAN) as an initiator. In order to thoroughly evaluate the synthesized material, X-Ray diffractometer (XRD) and Fourier transform infrared (FTIR) spectroscopy were used. These characterization methods revealed insights into the morphology, functionality, and crystallinity of nanocellulose. The removal of copper(II) ions is investigated by employing an atomic absorption spectrometer (AAS), focusing on three important factors: pH variation, initial concentration, and adsorbent dosage, which are carefully examined. Grafted nanocellulose demonstrates superior performance, achieving over 85% grafting efficiency. Optimal Cu(II) removal conditions are identified at pH 6, with an initial metal ion concentration of 30 ppm and an adsorbent dose of 2.2 g/L. This study not only addresses a critical concern in wastewater treatment, but also explores the potential of pandan leaf-derived nanocellulose as a sustainable solution for heavy metal removal. [ABSTRACT FROM AUTHOR]

In recent decades, renewable and biodegradable polysaccharide-based hydrogels have enjoyed wide applicability among them also as adsorbents for heavy metal removal from wastewaters. Herein we prepared hydrogel beads from iota and kappa carrageenans using a variety of salts as crosslinkers, that were tested for the first time in europium ion (Eu3+) sorption from an aqueous solution as representative lanthanide. The type of the salt, and especially the valance and the hydrated radius of the cation, were found to dictate hydrogel bead formation and structure and, therefore, the Eu3+ sorption yield. The results of ATR-FTIR, SEM and TGA analyses to characterize the iota carrageenan hydrogel beads that were prepared with alkali cations, before and after interaction with Eu3+, indicate that the adsorbent prepared with LiCl was much stiffer and more stable than those prepared with NaCl or KCl. The iota carrageenan beads that were prepared with LiCl were also reused 5 times while exhibiting high adsorption capacities. [ABSTRACT FROM AUTHOR]

Various industrial activities release heavy metal ions into the environment, which represent one of the major toxic pollutants owing to their severe effects on the environment, humans, and all living species. Despite several technological advances and breakthroughs, wastewater treatment remains a critical global issue. Traditional techniques are dedicated to extracting heavy metal ions from diverse wastewater origins, encompassing coagulation/flocculation, precipitation, flotation, and ion exchange. Their cost, side toxicity, or ineffectiveness often limit their large-scale use. Due to their adaptable design, simple operation, and reasonable cost, membrane filtration and adsorption have proven their efficiency in removing metals from wastewater. Recently, adsorption-based filters have appeared promising in treating water. Within this range, filters incorporating natural, synthetic, or hybrid adsorbents present an appealing alternative to conventional approaches. This review aims to list and describe the conventional and advanced wastewater treatment methods by comparing their efficiency, cost, and environmental impact. Adsorption-based filters were highlighted due to the significant advantages they can provide. [ABSTRACT FROM AUTHOR]

A facilely prepared composite based on Polyvinyl alcohol anchored‐ L‐cysteine (PVA‐L‐CYS) demonstrated efficient functionality in the elimination of heavy metals (Hg, Cr, Pb, and Cd) from working wastewater. The synthesis of the composite was validated through a comprehensive characterization utilizing various analytical techniques to ensure the composite's structural, chemical, and physical properties. At ambient temperature, pH of 4–5.5, interaction time of 15–20 minutes, and concentration of 200 mg/L metal ions, the composite exhibited a maximum retention capacity of 48.5, 25, 45.25, and 44.25 mg/g for Hg, Cr, Pb, and Cd, respectively. Langmuir modeling was establish to be more fitting to the practical results than Freundlich, providing theoretical values of 49.02, 25.97, 46.08, and 44.84 mg/g for Hg, Cr, Pb, and Cd, respectively. The kinetics of PVA‐L‐CYS composite was accurately predicted by model of the pseudo‐first‐order kinetic. Thermodynamic prospects indicated a spontaneous, exothermic, and favorable uptake process at low temperatures. Efficient elution of the heavy metal ions from the overloaded composite was performed using 1 M HNO3. In accordance with WHO and FAO guidelines, the successful elimination of working metal ions from wastewater utilizing the PVA‐L‐CYS composite was demonstrated in a single cycle before discharge into the marine environment. [ABSTRACT FROM AUTHOR]

A highly efficient hydrogel derived from D-Mannitol xanthate has been successfully synthesized using a free-radical solution copolymerization technique. An equimolar mixture of acrylonitrile (AN) and acrylic acid (AA) has been reacted with D-Mannitol xanthate (DMX) under inert atmosphere. Three distinct grades of D-Mannitol xanthate-based hydrogels viz. DMXHGs-1, DMXHGs-2, and DMXHGs-3, were prepared. Extensive analyses were conducted on the hydrogels using various methods such as UV, FT-IR, SEM, XRD, GPC, TGA and ΔpHPZC. The maximum swelling ratio of DMXHGs-3 was found to be 52122%, 50434% and 48576% for 24 h with water retention ratio of 80.98%, 78.64% and 79.22% for 30 h in distilled, tap and gray water respectively. These findings indicate the DMXHGs-3 hydrogel has remarkable swelling and water retention capacity. Comprehensive investigations were carried out to evaluate the hydrogel's remarkable adsorption capacity to act as an adsorbent for effectively removing hazardous metal ions. The highest removal percentages of 95.5% and 94.4% and maximum adsorption capacities of 523.56 mg g-1 and 462.96 mg g-1 were observed with DMXHGs-3 hydrogel for Cu2+ and Co2+ ions, respectively. Metal ion removal experiments were conducted by varying several parameters including dosage, pH, temperature, concentration, and time. The quantification of Cu2+ and Co2+ was accomplished using UV–visible spectroscopy. Present studies demonstrate the suitability of D-mannitol xanthate-based hydrogels for the efficient removal of toxic metal ions from wastewater [ABSTRACT FROM AUTHOR]

Toxic pollutants in the form of heavy metals are added through various anthropogenic activities daily into the aquatic ecosystem beyond their permissible limits, and their bioaccumulation capacity makes them hazardous substances for the survival of all organisms. Thus, their removal from aquatic ecosystems is the need of the hour. Treatment of wastewater containing heavy metals through biosorption is gaining popularity and is being explored all around the world due to its various advantages over conventional methods of treatment. Utilization of animal waste as a biomaterial could be the best solution to remove it from the ecosystem. Such treatment methods are a blessing for developing and underdeveloped countries due to their low cost. This paper provides in-depth details about heavy metals, their health implications, mechanisms of toxicity, modes of transportation, and conventional treatment approaches. A comprehensive understanding of the biosorption process, encompassing its world scenario, evolution, mechanisms, factors affecting the process, and advantages, will also be covered. Finally, animal wastes and their applicability in the removal of heavy metal pollutants from wastewater shall also be thoroughly reviewed, followed by their future utility and recommendations. [ABSTRACT FROM AUTHOR]

Heavy metals contamination poses a significant environmental threat, which requires the development of eco‐friendly bioremediation techniques. Present research work was conducted using wheat straw in submerged conditions for the growth of white rot fungus, Phlebia brevispora in the presence of varying concentrations of Cd, Pb, Ni, and Cr. The lignocellulolytic enzyme production ability of fungus was monitored. A wheat straw‐based fixed‐bed bioreactor was designed to treat metal‐containing water in continuous mode. The fungus showed a positive influence on laccase production, cellulase production, and lignin peroxidase activity. As observed through atomic absorption spectroscopy (AAS), Cr removal efficiency was 78%–80%, regardless of the initial metal concentration. The Cr was also found on the surface of fungal mycelium as per the results obtained from SEM–EDX. The continuous bioreactor achieved 98%–99% metal removal, making it a natural and cost‐effective solution for metal removal from wastewater using P. brevispora. [ABSTRACT FROM AUTHOR]

The efficient removal of Cr(VI) from the contaminated wastewater is an essential issue before discharge in a watercourse. Adsorption is viewed as the most promising technology for the removal of Cr(VI) because of its distinct advantages, including low operating cost, ease of operation, design simplicity, low maintenance, and high efficiency. Chitosan is a natural biopolymer with amine (-NH2) and hydroxyl (-OH) groups in its structure. The non-toxic, biodegradable, biocompatible, hydrophilic, and anti-bacterial nature of chitosan nanoparticles makes it an ideal bio-sorbent for the removal of heavy metal ions from contaminated wastewater. Weak mechanical strength, separation difficulties of chitosan nanoparticles from the aqueous phase, recyclability, and reusability are the potential limitations of utilizing the chitosan particles as a potential adsorbent for the removal of heavy metal ions from wastewater. There is increasing attention in fabricating magnetic chitosan nanoparticles (M-Ch-NPs) with surface modification of chitosan nanoparticles using magnetite to enhance the mechanical strength, reusablity and minimize the separation difficulties of chitosan nanoparticles from the aqueous phase. The present study reviews the various fabrication methods of chitosan nanoparticles and its utilization, environmental impacts, and challenges of utilizing M-Ch-NPs as an adsorbent for the Cr(VI) from contaminated wastewater. [ABSTRACT FROM AUTHOR]

Waterborne heavy metals pose significant threats to both the environment and public health, causing neurological damage, developmental disorders, organ damage, and cancer. It is essential to address the contamination of various water bodies by these hazardous substances due to their persistent nature and lack of biodegradability. This review thoroughly explores traditional and modern strategies utilized to remedy water sources contaminated with various heavy metals and evaluates the effectiveness and potential scalability of each method. A literature survey reveals several effective strategies for removing heavy metals from water: adsorption, flotation, ion exchange, chemical precipitation, membrane-based filtration, coagulation, flocculation, phytoremediation, and electrochemical methods. In our examination, we discussed the agents/adsorbents used, the efficiency of the removal technique, operating conditions, and the intrinsic advantages and disadvantages of each approach. Summarizing key findings, we noted a significant focus on adsorption techniques; however, challenges include selectively removing diverse ions, prolonged retention times, and cycling stability. While chemical and membrane methods are practical, persistent issues like large-volume sludge formation exist. Although electrical-based methods appear promising, solutions are needed for large-volume sludge and industrial-scale separation as well. Prioritizing real wastewater samples in heavy metals removal studies is crucial. Future research should emphasize eco-friendly, cost-effective methods. [ABSTRACT FROM AUTHOR]

During the last few decades, water pollution has become a growing concern at international level. To date, only a few Candida parapsilosis strains were successfully used in environmental remediation. In the present article, the strain C. parapsilosis CMGB-YT was studied for its ability to assimilate hydrophobic substrates and to produce biosurfactants with antimicrobial activity and positive effects on heavy metal removal from contaminated wastewaters. The strain C. parapsilosis CMGB-YT was grown on yeast peptone (YP) media with 1% n-decane, n-dodecane, n-tetradecane, n-hexadecane, as well as commercial sunflower and olive oils. The production of the biosurfactant was evaluated using the emulsification index (E24%). The surface properties and emulsifying stability of the biosurfactant were determined. The effect of the biosurfactant on the cell growth of two strains of Rhodotorula mucilaginosa and on their removal capacity of lead (0.032 g/L) and cadmium (0.030 g/L) ions from synthetic wastewater were also studied. The antimicrobial potential of 20 mg/mL and 40 mg/mL biosurfactant was established in the presence of pathogenic Candida krusei strains. C. parapsilosis CMGB-YT assimilated n-hexadecane with good rates over 216 h and produced an anionic glycolipidic biosurfactant with stable E24% towards long-chain carbon compounds at different temperatures, with an alkaline pH and high salinity (10% NaCl). The biosurfactant reduced the surface tension to 53.58 ± 0.42 mN/m, while the critical micellar concentration (CMC) was reached at 4.2% biosurfactant. The crude biosurfactant (5%) enhanced R. mucilaginosa growth in heavy metal-contaminated wastewater, increased chemical oxygen demand (COD) removal of up to 80%, and improved Cd2+ removal by 10%. Additionally, the concentrated biosurfactant effectively prevented Candida krusei biofilm formation. In conclusion, the biosurfactant produced by C. parapsilosis CMGB-YT demonstrates promising potential for the efficient treatment of wastewater contaminated with heavy metals and microbial pathogens. [ABSTRACT FROM AUTHOR]

AbstractThis study focuses on the synthesis of three grades of xanthates of natural polymeric material Xanthan gum (XG) by reacting it with Carbon disulfide (CS2) in basic medium at room temperature under inert atmosphere. The confirmation of the formation of Xanthan Gum Xanthates (XGX) has been done with the help of Ultraviolet (UV) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, point of zero-charge (PZC), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS) studies. DSC and XRD studies have been done to confirm the crystalline nature of the xanthates. The removal of Cu2+and Co2+ from the prepared grades was found to be 86.7%, 89.9% and 93.6% for Cu2+ and 86.1%, 88.8% and 93.1% for Co2+ respectively. Therefore, these xanthates can be employed for the eradication of such toxic metal ions from their synthetic solutions. The adsorption capacities of three grades of xanthates viz. XGX1, XGX2, and XGX3 were found to be 319.48, 303.03, and 325.73 mg/g for Cu(II) and 238.66, 246.91, and 230.41 mg/g and for Co(II) respectively, which are better than the adsorption capacities reported for various other adsorbents in literature. [ABSTRACT FROM AUTHOR]

Removal of heavy metal pollutants from wastewater is critical for preserving a clean environmental setting and guaranteeing universal well-being. Physical, chemical, and biological approaches have been devised for the removal of heavy metals from various wastewater sources. Methods used include electrocoagulation (EC) and adsorption (AD). Although both methods are reported to be efficiently applied in wastewater treatment, the EC method is impeded by high energy consumption, particularly when treating concentrated effluents, as it demands substantial current for coagulant formation. Alternatively, the AD process is hindered by adsorbent saturation and the competitive effects of specific chemicals. Here, we only found limited studies on integrated EC-AD combined process, where the AD and EC were either used in separate or combined system vessels to augment the removal efficiency of heavy metal ions from wastewater or synthetic solutions. It is imperative to conduct more studies on synergistic approaches that combine adsorption with other wastewater treatment methods to address current limits and optimize removal processes. The review identified current density, pH, time, temperature, and adsorbent dosages as factors influencing the EC-AD process in heavy in the removal of heavy metals from wastewater. Although electrocoagulation combined with adsorption has been explored in several studies which have been confined to synthetic effluents, limiting their relevance to real-world scenarios. Therefore, this review proposes for development and design of EC-AD combined technologies to exploit their strengths and minimize associated limitations. Overall, the combined strategies proved more effective and economical compared to individual adsorption and electrocoagulation methods. [ABSTRACT FROM AUTHOR]

Driven by concerns over polluted industrial wastewater, particularly heavy metals and dyes, this study explores biosorption using chemically cross-link chitosan derivatives as a sustainable and cost-effective depollution method. Chitosan cross-linking employs either water-soluble polymers and agents like glutaraldehyde or copolymerization of hydrophilic monomers with a cross-linker. Chemical cross-linking of polymers has emerged as a promising approach to enhance the wet-strength properties of materials. The chitosan thus extracted, as powder or gel, was used to adsorb heavy metals (lead (Pb2+) and copper (Cu2+)) and dyes (methylene blue (MB) and crystal violet (CV)). Extensive analysis of the physicochemical properties of both the powder and hydrogel adsorbents was conducted using a range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM), as well as 1H and 13C nuclear magnetic resonance (NMR). To gain a comprehensive understanding of the sorption process, the effect of contact time, pH, concentration, and temperature was investigated. The adsorption capacity of chitosan powder for Cu(II), Pb(II), methylene blue (MB), and crystal violet (CV) was subsequently determined as follows: 99, 75, 98, and 80%, respectively. In addition, the adsorption capacity of chitosan hydrogel for Cu(II), Pb(II), MB, and CV was as follows: 85, 95, 85, and 98%, respectively. The experimental data obtained were analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models. The isotherm study revealed that the adsorption equilibrium is well fitted to the Freundlich isotherm (R2 = 0.998), and the sorption capacity of both chitosan powder and hydrogel was found to be exceptionally high (approximately 98%) with the adsorbent favoring multilayer adsorption. Besides, Dubinin has given an indication that the sorption process was dominated by Van der Waals physical forces at all studied temperatures. [ABSTRACT FROM AUTHOR]

The discharge of lead and cadmium wastewater, along with the pollution caused by phosphogypsum, represents a particularly urgent environmental issue. This study employed a straightforward hydrothermal method to convert phosphogypsum into porous calcium silicate hydrate (P-CSH), which was then used to remove and recover Pb(II) and Cd(II) from wastewater. The adsorption capacities of P-CSH for Pb(II) and Cd(II) were notably high at 989.3 mg/g and 290.3 mg/g, respectively. The adsorption processes adhered to the pseudo-second-order kinetics model and the Langmuir isotherm model. Due to identical adsorption sites on P-CSH for both Pb(II) and Cd(II), competitive interaction occurred when both ions were present simultaneously. Additionally, the adsorption efficacy was minimally impacted by the presence of common coexisting cations in wastewater. The dominant mechanisms for removing Pb(II) and Cd(II) via P-CSH were chemical precipitation and surface complexation. Moreover, the adsorbed heavy metals were efficiently separated and reclaimed from the wastewater through a stepwise desorption process. The primary components of the residue from stepwise desorption were quartz and amorphous SiO2. Following dissolution via pressurized alkaline leaching, this residue could be recycled for synthesizing P-CSH. This research offered a new strategy for the resourceful use of phosphogypsum and heavy metal wastewater. [ABSTRACT FROM AUTHOR]

The necessity to eliminate nickel (Ni) from wastewater stems from its environmental and health hazards. To enhance the Ni adsorption capacity, this research applied a copper sulfate–ammonia complex (tetraamminecopper (II) sulfate monohydrate, [Cu(NH3)4]SO4·H2O) as a modifying agent for a Phragmites australis-based activated carbon preparation. The physiochemical properties of powdered activated carbon (PAC) and a modified form ([Cu(NH3)4]-PAC) were examined by measuring their surface areas, analyzing their elemental composition, and using Boehm's titration method. Batch experiments were conducted to investigate the impact of various factors, such as Ni(II) concentration, contact time, pH, and ionic strength, on its substance adsorption capabilities. Additionally, the adsorption mechanisms of Ni(II) onto activated carbon were elucidated via Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The findings indicated that modified activated carbon ([Cu(NH3)4]-PAC) exhibited a lower surface area and total volume than the original activated carbon (PAC). The modification of PAC enhanced its surface's relative oxygen and nitrogen content, indicating the incorporation of functional groups containing these elements. Furthermore, the modified activated carbon, [Cu(NH3)4]-PAC, exhibited superior adsorption capacity relative to unmodified PAC. Both adsorbents' adsorption behaviors conformed to the Langmuir model and the pseudo-second-order kinetics model. The Ni(II) removal efficiency of PAC and [Cu(NH3)4]-PAC diminished progressively with rising ionic strength. Modified activated carbon [Cu(NH3)4]-PAC demonstrated notable pH buffering and adaptability. The adsorption mechanism for Ni(II) on activated carbon involves surface complexation, cation exchange, and electrostatic interaction. This research presents a cost-efficient preparation technique for preparing activated carbon with enhanced Ni(II) removal capabilities from wastewater and elucidates its underlying adsorption mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, two flower-like magnesium silicate nanomaterials were prepared. These and another two commercial magnesium silicate materials were characterized using a scanning electron microscope, the N2 adsorption–desorption method, and other methods. The structure–activity relationship between the adsorption performance of these four magnesium silicate materials and their specific surface area, pore size distribution, and pore structure was compared. The results showed that the 3-FMS modified by sodium dodecyl sulfonate (SDS) had the largest specific surface area and pore size, the best adsorption performance, and the largest experimental equilibrium adsorption capacity (qe,exp) for Co2+, reaching 190.01 mg/g, and Cr3+, reaching 208.89 mg/g. The adsorption behavior of the four materials for Co2+ and Cr3+ both fitted the pseudo-second-order kinetic model and Langmuir adsorption model, indicating that chemical monolayer uniform adsorption was the dominant adsorption process. Among them, the theoretical adsorption capacity (qm) of 3-FMS was the highest, reaching 207.62 mg/g for Co2+ and 230.85 mg/g for Cr3+. Through further research, it was found that the four materials mainly removed Co2+ and Cr3+ through electrostatic adsorption, surface metal ions (Mg2+), and acidic groups (-OH and -SO3H) exchanging with ions in solution. The adsorption performance of two self-made flower-like magnesium silicate materials for Co2+ and Cr3+ was superior to that of two commercial magnesium silicates. [ABSTRACT FROM AUTHOR]

To improve the removal capacity of rice straw biochar for heavy metals in acidic mine wastewater, magnesium-modified rice straw biochar (MBC) was prepared by impregnation-pyrolysis method. The effects of impregnation ratio, solution pH,adsorption time,and initial concentration on the removal of Cd(II) and Pb(II) from acid mine wastewater by MBC were investigated through batch adsorption experiments, and the features of MBC before and after adsorption were analyzed by characterisation techniques to explore the potential adsorption mechanisms. The results showed that the MBC prepared by impregnation-pyrolysis possessed a well-developed pore structure. The adsorption experiments showed that the removal efficiency for 10 mg/L of Pb(II) and Cd(II) by MBC reached the optimum values of 93. 58% and 97. 95% at impregnation ratio 2 : 1 and solution pH 5. 0 respectively. The removal process of Cd( II) and Pb(II) by MBC was consistent with the pseudo second order kinetic model and Langmuir adsorption isotherm model. According to the Langmuir model,the maximum adsorption capacities of MBC for Cd(II) and Pb(II) were 90. 45 mg/g and 138. 50 mg/g, respectively. FTIR and XRD analyses showed that the removal mechanism of Cd (II) and Pb (II) by MBC contained complexation, co-precipitation, ion exchange, and electrostatic interaction. After five regenerations, the removal efficiency of Cd(II) and Pb(II) by MBC was maintained at 85. 62% and 80. 16%, respectively. The above results indicated that MBC had great potential for treating acid mine wastewater containing Cd(II) and Pb(II). [ABSTRACT FROM AUTHOR]

This study innovatively added biochar to optimize regulation in the neutralization process of simulated acid mine drainage (AMD) and recovered a new type of matrix layered double hydroxides (MLDH), which can be used to remove copper (Cu(II)) and cadmium (Cd(II)) from wastewater. A series of batch experiments show that MLDH with strong selective removal ability of Cu(II) and Cd(II) can be successfully obtained by adding biochar (BC) at pH = 5 end in the neutralization process. Kinetic and isotherm modeling studies indicated that the removal of Cu(II) and Cd(II) by the MLDH was a chemical multilayer adsorption process. The removal mechanism of Cu(II) and Cd(II) was further analyzed through related characterization analysis with contribution rate calculation: the removal rates of Cu(II) and Cd(II) by ion exchange were 42.7% and 26%, while that by precipitation were 34.5% and 49.9%, respectively. This study can provide a theoretical reference and experimental basis for the recovery and utilization of valuable by-products in AMD and the treatment of heavy metal wastewater. [ABSTRACT FROM AUTHOR]